Cardiac hypertrophy determines digitalis action on intracellular Ca2+ in human myocardium.
Ventricular hypertrophy alters transporters associated with digitalis action, but the outcome of digitalis treatment on intracellular cations in the hypertrophied human myocardium remains unknown. Using double-barreled Ca2+-selective microelectrodes, we simultaneously measured Ca2+ activity and membrane potential in myocardial samples from patients without and with ventricular hypertrophy, prior to and following exposure to strophanthidin, a prototype digitalis. We found that ventricular hypertrophy is associated with greater strophanthidin-induced increase in diastolic Ca2+ levels compared to that observed in the absence of hypertrophy. Furthermore, in hypertrophied myocardium the magnitude of the increase in Ca2+ induced by strophanthidin was inversely related to increase in myocardial mass. Thus, the extent of ventricular hypertrophy determines digitalis action on intracellular Ca2+ within the human myocardium.
Lopez
J R
JR
Centro de Biofisica y Bioquimica, Instituto Venezolano de Investigaciones Cientificas, Caracas, Venezuela.
Linares
N
N
Brady
P A
PA
Terzic
A
A
D000328:Adult; D000368:Aged; D002118:Calcium / Q000378:metabolism*; D004070:Digitalis; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000188:drug therapy* / Q000378:metabolism; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism*; D010946:Plants, Medicinal; D010947:Plants, Toxic; D013327:Strophanthidin / Q000627:therapeutic use*
D013327:Strophanthidin; D002118:Calcium